I'm guessing the reliability has to do with all of MS' (free?) e-mail offerings then? Because they're all accessed the same way, regardless of the domain you pick.
And I'm not aware of failing to receive any other legitimate e-mails. (Bar a couple of days years ago when there were issues and hardly anything got through.) Thought there were some issues for a while, but eventually got around to verifying and turned out it was fine, problem was on the other side, what I was expecting wasn't sent.

And there is an amount of time without activity after which they inactivate and subsequently delete free addresses.

Yeah, the emails informing me that they were closing hotmail was years ago. Like, maybe around 2012 i think it was?

The purchase was in '97 apparently, but I wouldn't say they ever "closed" it. It was supposed to be rebranded to Windows Live Mail in 2005 but in 2007 they stuck with Windows Live Hotmail, then in 2012 yeah, they phased it out to replace it with Outlook.com, with a period during which you could switch back and forth between the UIs and features. But existing users were just migrated, with an option to change the address to @outlook.com if desired. If you didn't want to, you just kept your address, but technically ended up using Outlook.com once the switch was enforced.
My bookmark is actually still for hotmail.com, then it redirects me.

Ah, that was all lost on me. I just remember getting emails on my yahoo account that my hotmail wasn't going to be provided anymore. Kinda sad 'cause i had emails i wanted to keep. The thing was, i got the emails late, too, and i couldn't get in so i gave up.